Detecting and tracking damage to an aeroengine fan or an impact of a foreign object thereagainst

Abstract

A system for detecting deformation of a fan for an aeroengine, the fan including a rotor including plural blades made of composite material including woven fibers. At least one of the fibers in each of the blades is an optical fiber including at least one portion defining a Bragg grating. The system further includes a transceiver connected to the optical fiber and configured to send an optical signal into the optical fiber and to receive an optical signal in response from the optical fiber, and a detector module connected to the transceiver to detect deformation of the fan when the received optical signal presents correlation with a predetermined signature of a damped impact on a blade at a determined speed of rotation. This deformation may be the result of a foreign object impacting against a blade of the fan or may follow from variation in an internal defect.

The invention claimed is: 
     
       1. A fan for an aeroengine, comprising:
 a rotor including a plurality of blades made of composite material including woven fibers; and 
 a system for detecting deformation resulting from an impact of a body against the fan; 
 wherein at least one of the fibers in each of the blades is an optical fiber including at least one portion defining a Bragg grating; 
 the fan further comprising: 
 a transceiver connected to the optical fiber and configured to send an optical signal into the optical fiber and to receive an optical signal in response from the optical fiber; and 
 a detector module connected to the transceiver to detect deformation of the fan when the received optical signal presents correlation with a predetermined signature of a damped impact on a blade at a determined speed of rotation. 
 
     
     
       2. A fan according to  claim 1 , wherein the body impacting the fan is a foreign object damage (FOD) or a domestic object damage (DOD). 
     
     
       3. A fan according to  claim 2 , wherein the detector module is configured to determine a mass for the body by analyzing the received optical signal. 
     
     
       4. A fan according to  claim 3 , wherein a plurality of the fibers in each of the blades are optical fibers. 
     
     
       5. A fan according to  claim 4 , wherein the detector module is configured to determine a location for the impact of the body by analyzing the received optical signal. 
     
     
       6. A fan according  claim 1 , further comprising a stator-to-rotor optical coupler connecting the transceiver to the optical fiber. 
     
     
       7. A fan according to  claim 1 , wherein the transceiver is carried by the rotor, the detector module configured to communicate with the transceiver by a wireless connection via a communications unit. 
     
     
       8. A fan according to  claim 1 , wherein the detector module is incorporated in an electronic unit configured to store information relating to the detected deformation, for identifying the blade, and for transmitting deformation and identification information to a maintenance system. 
     
     
       9. A fan according to  claim 8 , further comprising:
 receiver means for receiving the deformation and identification information; and 
 analysis means for subjecting the deformation information to modal analysis or to analysis of resonances synchronous with engine speed, to identify modal parameters relating to each blade and to track variation of the parameters to detect an appearance of defects and their progress over the blades of the fan. 
 
     
     
       10. An aeroengine comprising a fan according  claim 1 . 
     
     
       11. A method of detecting deformation resulting of an impact of a body against a fan of an aeroengine, the fan including a rotor including a plurality of blades made of composite material including woven fibers and a system for detecting deformation, the method comprising:
 sending an optical signal into at least one of the fibers in each of the blades, which fiber is an optical fiber; 
 receiving an optical signal coming from the optical fiber; and 
 correlating the received optical signal and a predetermined signature for a damped impact against a blade at a determined speed of rotation to detect deformation of the fan. 
 
     
     
       12. A detection method according to  claim 11 , wherein the body impacting the fan is a foreign object damage (FOD) or a domestic object damage (DOD). 
     
     
       13. A detection method according to  claim 12 , further comprising determining a mass for the body and a location for the impact of the body against the fan by analyzing the received optical signal. 
     
     
       14. A detection method according to  claim 11 , further comprising subjecting each of the signals to modal analysis or to analysis of resonances synchronous with engine speed, to identify modal parameters relating to each blade and to track variation in the modal parameters to detect an appearance of defects and their progress over the blades.